Heat collection receiver and solar thermal power generation device

ABSTRACT

A heat collection receiver includes a heat absorption body and a support body. The heat absorption body includes at least one honeycomb unit in which a plurality of flow paths through which a heat medium passes are provided in parallel with each other. The at least one honeycomb unit includes porous silicon carbide and silicon that fills pores in the porous silicon carbide. A surface region of the at least one honeycomb unit includes a porous layer which includes pores in a predetermined depth from the surface. The surface region is irradiated with solar light. The pores of the porous layer are not filled with the silicon. The support body accommodates and supports the heat absorption body and the heat medium flows through the support body.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of InternationalApplication No. PCT/JP2011/074515, filed Oct. 25, 2011, which claimspriority to Japanese Patent Application No. 2010-239007, filed Oct. 25,2010. The contents of these applications are incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat collection receiver and a solarthermal power generation device.

2. Discussion of the Background

Solar thermal power generation is known as a power generation methodusing the sun. In the solar thermal power generation, light that isemitted from the sun is condensed through a reflective mirror or thelike, and a steam turbine is made to operate by using the obtained solarheat so as to generate electricity. In this solar thermal generation, agreenhouse effect gas such as carbon dioxide is not generated during thepower generation, and heat may be accumulated, and thus the powergeneration is possible under a cloudy skies or at nighttime.Accordingly, the solar thermal power generation has attracted muchattention as a promising power generation method in the future.

The solar thermal power generation type is largely divided into twokinds of a trough type and a tower type. The tower-type solar thermalpower generation is a power generation type in which solar light isfocused to a heat collection receiver of a tower provided at a centralportion by using a plurality of planar mirrors called a heliostat so asto condense the light, and electricity is generated using heat of thecondensed solar light. The heliostat is a planar mirror of several metersquare. In the tower-type solar thermal power generation, the solarlight, which is collected using several hundred sheets of heliostats orseveral thousand sheets of heliostats, may be focused to one place.Therefore, the heat collection receiver may be heated to approximately1,000° C., and the tower-type solar thermal power generation has acharacteristic in which thermal efficiency is excellent.

As the heat collection receiver for the tower-type solar thermal powergeneration, U.S. Pat. No. 6,003,508 discloses a heat collectionreceiver. In the heat collection receiver, a heat absorption body, whichincludes a plurality of gas flow paths through which a heat medium flowsand which is formed from silicon carbide, or silicon and siliconcarbide, is accommodated in and supported by a funnel-shaped supportbody.

In the heat collection receiver, a heat medium such as the air and amixed gas containing the air is made to pass through the flow paths ofthe heat absorption body that is heated, and accordingly, the heatmedium can obtain heat. In the tower-type solar thermal powergeneration, water is boiled by the obtained heat to produce steam, and asteam turbine is made to operate so as to generate electricity.

It is necessary for the heat collection receiver to absorb the emittedsolar light through the heliostat and to effectively convert the solarlight into heat.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a heat collectionreceiver includes a heat absorption body and a support body. The heatabsorption body includes at least one honeycomb unit in which aplurality of flow paths through which a heat medium passes are providedin parallel with each other. The at least one honeycomb unit includesporous silicon carbide and silicon that fills pores in the poroussilicon carbide. A surface region of the at least one honeycomb unitincludes a porous layer which includes pores in a predetermined depthfrom the surface. The surface region is irradiated with solar light. Thepores of the porous layer are not filled with the silicon. The supportbody accommodates and supports the heat absorption body and the heatmedium flows through the support body.

According to another aspect of the present invention, a solar thermalpower generation device includes the heat collection receiver.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings.

FIG. 1A is a longitudinal cross-sectional diagram schematicallyillustrating a heat collection receiver related to a first embodiment ofthe invention, and FIG. 1B is a cross-sectional diagram taken along anA-A line of the heat collection receiver shown in FIG. 1A.

FIG. 2 is an enlarged cross-sectional diagram illustrating the vicinityof a surface region of a honeycomb unit making up the heat collectionreceiver shown in FIG. 1A.

FIG. 3A is a front elevational diagram schematically illustrating areceiver array making up a solar thermal power generation device of theembodiment of the invention, and FIG. 3B is a cross-sectional diagramtaken along a B-B line of the receiver array shown in FIG. 3A.

FIG. 4 is an explanatory diagram schematically illustrating a solarthermal power generation device related to a third embodiment of theinvention.

FIG. 5 is a graph illustrating evaluation results of Example 1 andComparative Examples 1 and 2 of the invention.

DESCRIPTION OF THE EMBODIMENTS

That is, according to an embodiment of the invention, there is provideda heat collection receiver that is used in a solar thermal powergeneration device. The heat collection receiver includes a heatabsorption body that includes one or a plurality of honeycomb units inwhich a plurality of flow paths through which a heat medium passes areformed, and a support body which accommodates and supports the heatabsorption body and through which the heat medium flows. The honeycombunit includes porous silicon carbide, and silicon that fills pores inthe porous silicon carbide. In regard to a surface that is irradiatedwith solar light, a surface region in a predetermined depth from thesurface is formed from a porous layer, and pores of the porous layer arenot filled with the silicon.

In the heat collection receiver according to the embodiment, since thehoneycomb unit includes porous silicon carbide, and silicon that fillspores in the porous silicon carbide, the heat collection receiverbecomes a dense body, and thus a heat accumulation property of the heatabsorption body increases. In addition, the dense body in which thepores of the porous silicon carbide are filled with silicon has a highthermal conductivity, and thus heat that is obtained may be smoothlytransferred to a heat medium such as the air.

In addition, in the heat collection receiver according to theembodiment, since in regard to a surface, which is irradiated with solarlight, of the honeycomb unit, a surface region at a predetermined depthfrom the surface is formed from a porous layer, and pores of the porouslayer are not filled with the silicon, it is possible to prevent solarlight from being reflected by silicon. In addition, in the heatcollection receiver according to the embodiment, it is easy for solarlight to enter the inside of the porous layer in the surface of thehoneycomb unit, and light reflected inside the porous layer comes intocontact with a separate wall inside the porous layer. Accordingly, it isdifficult for the reflected light to be emitted to the outside. As aresult, the emitted solar light may be effectively converted into heat,and thus power generation may be effectively performed.

In the heat collection receiver, the honeycomb unit may further includeporous carbon, and the surface region of the honeycomb unit may beformed from a porous carbon layer. In such case, a solar lightreflectance of the surface layer itself of the honeycomb unit decreases,and thus heat absorption efficiency increases.

In the heat collection receiver, the surface region of the honeycombunit may have a depth of 500 nm or more from the surface. This is forthe following reasons. When the depth of the surface region is less than500 nm, since the surface region is too thin, reflectance of solar lightdue to silicon contained in the honeycomb unit occurs, and thus the heatabsorption efficiency decreases.

In the heat collection receiver, flow paths of 31.0 to 93.0 per cm² maybe formed in the honeycomb unit, a thickness of a wall portion betweenthe flow paths in the honeycomb unit may be 0.1 to 0.5 mm, a porosity ofthe porous silicon carbide may be 35 to 60%, and an average pore sizemay be 5 to 30 μm. In such porosity and a pore size, the porous siliconcarbide is easily filled with silicon. In a case where the flow path ofthe dense honeycomb unit, which is obtained as described above, isconfigured in this manner, when a heat medium flows through the flowpath, heat is effectively transferred from the heat absorption bodyformed from the honeycomb unit to the heat medium, and as a resultthereof, the power generation may be performed with high efficiency.

In the honeycomb unit related to the embodiment of the invention, it ispreferable that when a cross-section orthogonal to the flow path isformed, the number of flow paths per 1 cm² be 31.0 to 93.0 per cm². Whenthe number of the flow paths of the honeycomb unit is less than 31.0 percm², since the number of the flow paths of the honeycomb unit is small,it is difficult for the honeycomb unit to effectively perform heatexchange with the heat medium. On the other hand, when the number of theflow paths of the honeycomb unit exceeds 93.0 per cm², a cross-sectionalarea of one flow path of the honeycomb unit becomes small, and thus itis difficult for the heat medium to pass through the flow path.

In the heat collection receiver, a heat insulation material may beinterposed between the heat absorption body and the support body. Insuch case, the heat absorption body may be reliably held by the heatinsulation material, and due to this heat insulation material, it ispossible to effectively prevent heat from escaping from the heatabsorption body to the support body.

In the heat collection receiver, the heat absorption body may beconfigured in such a manner that the plurality of honeycomb units arebonded to each other through an adhesive layer that is formed on a sidesurface. In such case, the honeycomb units are bonded to each other in areliable manner, and thus it is possible to prevent part of thehoneycomb units from falling out due to a flow force of the heat mediumthat flows through the flow path of the honeycomb unit that is includedin the heat absorption body.

In the heat collection receiver, the heat absorption body may beconfigured in such a manner that the plurality of honeycomb units arebonded to each other through a silicon layer that is formed on a sidesurface. In such case, the honeycomb units are bonded to each other in areliable manner, and thus it is possible to prevent part of thehoneycomb units from falling out due to a flow force of the heat mediumthat flows through the flow paths of the honeycomb unit that is includedin the heat absorption body.

According to another embodiment of the invention, there is a provided asolar thermal power generation device in which the above-described heatcollection receiver is used. In the embodiment, the emitted solar lightmay be effectively converted into heat, and thus power generation may beeffectively performed.

The embodiments will now be described with reference to the accompanyingdrawings, wherein like reference numerals designate corresponding oridentical elements throughout the various drawings.

First Embodiment

Hereinafter, a first embodiment that is an embodiment of a heatcollection receiver of the invention will be described with reference tothe attached drawings. FIG. 1A shows a longitudinal cross-sectionaldiagram schematically illustrating a heat collection receiver related tothe first embodiment of the invention, and FIG. 1B shows across-sectional diagram taken along an A-A line of the heat collectionreceiver shown in FIG. 1A. FIG. 1A shows a longitudinal cross-sectionaldiagram that is obtained by cutting a honeycomb unit, which makes up aheat absorption body accommodated in the heat collection receiver, in adirection parallel to a flow path, and FIG. 1B shows a cross-sectionaldiagram illustrating a cross-section orthogonal to the flow path. FIG. 2shows an enlarged cross-sectional diagram illustrating the vicinity of asurface region of the honeycomb unit related to the first embodiment ofthe invention.

As shown in FIGS. 1A, 1B, and FIG. 2, a heat collection receiver 10related to the embodiment of the invention includes a heat absorptionbody 11 in which a plurality of honeycomb units 13 are bonded to eachother through silicon 15 (an adhesive layer formed from silicon,hereinafter, also referred to as a silicon layer) that functions as anadhesive, and a support body 12 which accommodates and support the heatabsorption body 11 and through which a heat medium 14 flows. In each ofthe honeycomb units 13, a plurality of flow paths 13 b, through which aheat medium 14 flows, are provided in parallel with each other. Inaddition, a heat insulation material 17 formed from an inorganic fiberis interposed between the heat absorption body 11 and the support body12, and thus the heat absorption body 11 is supported by and fixed tothe support body 12 through the heat insulation material 17.

The honeycomb unit 13 includes a porous silicon carbide 16 having openpores, and silicon 15 that fills the open pores of the porous siliconcarbide 16. In regard to a surface of the honeycomb unit 13, which isirradiated with solar light 18, a surface region at a predetermineddepth from the surface is formed from a porous layer 13 a. FIG. 2 showsa detailed structure of the porous layer 13 a of the surface region ofthe honeycomb unit 13. The pores other than pores of the porous layer 13a are filled with silicon 15, whereby a dense body is obtained. However,the silicon 15 is not present at a portion of the porous layer 13 a, andthus the porous layer 13 a is configured as a porous body having openpores.

Accordingly, it is difficult for solar light 18 reflected by a heliostatto come into direct contact with the silicon 15, and thus it is possibleto prevent the solar light 18 from being reflected by the silicon 15. Inaddition, since the surface region of the honeycomb unit 13 is formedfrom the porous layer 13 a, it is easy for the solar light 18 to enterthe inside of the porous layer 13 a, and light reflected inside theporous layer 13 a comes into contact with a separate wall inside theporous layer 13 a. Accordingly, it is difficult for the reflected lightto be emitted to the outside. As a result, the emitted solar light 18may be effectively converted into heat.

The porous layer 13 a may be formed from only the porous layer siliconcarbide 16. In a case where the porous layer 13 a is formed from theporous silicon carbide 16, the entirety of the open pores of the poroussilicon carbide 16 are filled with the silicon 15, and then the silicon15 that is filled once in the surface region of the porous siliconcarbide 16 is removed by any method, whereby the honeycomb unit 13 maybe produced. In addition, the porous layer 13 a may be a layer in whichthe porous silicon carbide 16 exposed by removing the silicon 15 isfurther converted into carbon.

Examples of a method of converting the porous silicon carbide 16 in theporous layer 13 a into carbon include a method in which an ambientatmosphere of the porous silicon carbide 16 is set to a vacuumatmosphere of 0.8 Torr or less, and then a heating treatment isperformed at 1,600 to 1,700° C. for 96 hours or more. According to this,silicon comes out from silicon carbide, and thus silicon carbide isconverted into carbon.

In a case where the porous layer 13 a is formed from silicon carbide, itis preferable that the lower limit of the thickness of the surfaceregion in the porous layer 13 a be 400 nm (0.40 μm), and more preferably40 μm. The upper limit thereof is preferably 2 mm. In a case where theporous layer 13 a is formed from carbon, it is preferable that the lowerlimit of the thickness of the porous layer 13 a be 400 nm (0.40 μm), andmore preferably 650 nm (0.65 μm). The upper limit thereof is preferably2 mm.

Within this range, it is difficult for the porous layer 13 a to reflectsolar light, and the porous layer 13 a may satisfactorily absorb thesolar light. In addition, the heat transfer of the collected heat to theheat medium becomes satisfactory. When the thickness of the surfaceregion in the porous layer 13 a is smaller than the lower limit, thesolar light reaches a dense layer. On the other hand, when the thicknessof the surface region in the porous layer 13 a is larger than the upperlimit, a region of the dense body relatively decreases, and thus anamount of heat transfer to the heat medium is apt to decrease.

In a case where the porous layer 13 a is formed from carbon, since it iseasy for carbon to absorb the solar light 18, the thickness of theporous layer 13 a may be set to be small.

Particularly, in a case where the porous layer 13 a is formed fromsilicon carbide, it is preferable that the thickness of the surfaceregion be 0.40 to 78 μm, and more preferably 47 to 78 μm. In a casewhere the porous layer 13 a is formed from carbon, it is preferable thatthe thickness of the surface region be 0.40 to 78 μm, and morepreferably 0.65 to 78 μm.

In the heat collection receiver 10 related to the embodiment of theinvention, it is preferable that a porosity of the porous siliconcarbide 16 be 35 to 60%. When the porosity is less than 35%, part of thepores becomes a closed pore, and thus it is difficult for the entiretyof the pores to be filled with the silicon 15. On the other hand, whenthe porosity exceeds 60%, the strength of the honeycomb unit 13decreases, and thus it is easy for the honeycomb unit 13 to be brokendue to repetition of temperature rise and fall (thermal hysteresis) ofthe honeycomb unit 13.

In addition, the porosity is measured by a mercury intrusion method.

It is preferable that an average pore size of the porous silicon carbide16 be 5 to 30 μm. When the average pore size of the porous siliconcarbide 16 is less than 5 μm, it is easy for part of the pores to be aclosed pore, and thus it is difficult for the pores to be filled withthe silicon 15. On the other hand, when the average pore size of theporous silicon carbide 16 exceeds 30 μm, the mechanical strength of theporous silicon carbide 16 decreases, and thus the strength of thehoneycomb unit 13 also decreases.

It is preferable that 15 to 50 parts by weight of the silicon 15 beimpregnated with respect to 100 parts by weight of the porous siliconcarbide. When the silicon impregnation in the porous silicon carbide 16is performed within this range, the silicon 15 is buried in the openpores of the porous silicon carbide 16 and thus the honeycomb unitbecomes a dense body.

In the honeycomb unit 13 related to the embodiment of the invention,when a cross-section orthogonal to each flow path 13 b is formed, it ispreferable that the number of the flow paths 13 b per 1 cm² be 31.0 to93.0 per cm². When the number of the flow paths 13 b of the honeycombunit 13 is less than 31.0 per cm², since the number of the flow paths 13b of the honeycomb unit 13 is small, it is difficult for the honeycombunit 13 to effectively perform heat exchange with the heat medium 14. Onthe other hand, when the number of the flow paths 13 b of the honeycombunit 13 exceeds 93.0 per cm², a cross-sectional area of one flow path 13b of the honeycomb unit 13 becomes small, and thus it is difficult forthe heat medium 14 to pass through the flow path 13 b.

In addition, it is preferable that the thickness of a wall portion ofthe honeycomb unit 13 between the flow paths be 0.1 to 0.5 mm. When thethickness of the wall portion of the honeycomb unit 13 is less than 0.1mm, the mechanical strength of the wall portion of the honeycomb unitdecreases, and thus it is easy for the honeycomb unit to be broken. Onthe other hand, the thickness of the wall portion of the honeycomb unit13 exceeds 0.5 mm, the wall portion of the honeycomb unit 13 becomes toothick, and thus a flow amount of the heat medium 14 with respect to anarea of the honeycomb unit 13 decreases. As a result, heat efficiencydecreases.

In the embodiment of the invention, the porous silicon carbide 16 isused as porous ceramic that is filled with the silicon 15, but anotherporous ceramic may be used. Examples of another porous ceramic includenitride ceramics such as aluminum nitride, silicon nitride, and boronnitride, carbide ceramics such as silicon carbide, zirconium carbide,and tantalum carbide, and the like. These kinds of ceramics have highthermal conductivity in themselves.

In a case of producing the heat absorption body 11 using the pluralityof honeycomb units 13, silicon 15 that is the same material as thesilicon 15 fills inside each of the honeycomb units 13 (the poroussilicon carbide 16) may be used as an adhesive to form an adhesivelayer, and then the honeycomb units 13 may be bonded to each other bythe adhesive layer, whereby the heat absorption body 11 may be provided.

In addition, in FIG. 1B, the cross-sectional shape of the flow path 13 bof the honeycomb unit 13 is set to a rectangular shape, but thecross-sectional shape of the flow path 13 b of the honeycomb unit 13 isnot particularly limited, and may be a hexagonal shape or the like. Inaddition, the cross-sectional shape of the support body 12 shown in FIG.1B is also a rectangular shape, but the cross-sectional shape of thesupport body 12 is not particularly limited to the rectangular shape,and may be a hexagonal shape or the like.

As described above, although the cross-sectional shape of the supportbody 12 viewed from the front side as shown in FIG. 1B is a rectangularshape, a hexagonal shape, or the like, the entire shape of the supportbody 12 is a funnel shape. That is, a cross-section (a cross-sectionthat is parallel to a surface, which receives the solar light 18, of theheat absorption body 11) of a heat collection portion 12 a has a largearea, the heat collection portion 12 a being a portion in which the heatabsorption body 11 is accommodated and to which the heat medium 14flows. However, as the cross-section moves in a direction parallel to anexit direction of the heat medium 14, the cross-sectional area graduallydecreases, and then the cross-section area becomes approximatelyconstant at the gas outlet 12 b.

Although a material of the support body 12 is not particularly limited,since the heat absorption body 11 reaches a temperature of approximately1,000° C., it is preferable that the support body 12 have heatresistance, and thus metal or ceramic is preferable as the material.

Examples of the metallic material include iron, nickel, chrome,aluminum, tungsten, molybdenum, titanium, lead, copper, zinc, alloys ofthese metals, and the like. In addition, examples of the ceramic includenitride ceramic such as aluminum nitride, silicon nitride, boronnitride, and titanium nitride, carbide ceramic such as zirconiumcarbide, titanium carbide, tantalum carbide, and tungsten carbide, oxideceramic such as silica, alumina, mullite, and zirconia, and the like. Inaddition to these, examples of the material of the support body 12include a composite of metal and nitride ceramic, a composite of metaland carbide ceramic, and the like. Among these, a ceramic such asalumina and silicon carbide is preferable from a viewpoint of heatresistance.

In the heat collection receiver 10 of the embodiment of the invention,the heat insulation material 17 is interposed between the heatabsorption body 11 and the support body 12.

A material of the heat insulation material 17 is not particularlylimited and may be a material including various inorganic materials suchas an inorganic fiber, an inorganic particle, and an inorganic binder, amat type formed from the inorganic fiber is preferable. In thisembodiment, an example using a mat, which is formed from the inorganicfiber and has a rectangular shape in a plan view, as a heat insulationmaterial will be described below.

The heat insulation material 17 is configured in such a manner that oneor a plurality of mats, which are formed from the inorganic fiber andhas a rectangular shape in a plan view, are laminated, and the heatinsulation material 17 is accommodated in the support body 12 in a stateof being wound around the side surface of the heat absorption body 11,whereby the heat absorption body 11 may be supported and fixed at theinside the support body 12.

The inorganic fiber making up the mat is not particularly limited andmay be an alumina-silica fiber, an alumina fiber, a silica fiber, or thelike. A material of the inorganic fiber may be changed in accordancewith properties such as heat resistance and wind erosion resistance thatare required for a sealing material. In a case of using thealumina-silica fiber as the inorganic fiber, it is preferable to use afiber in which, for example, a compositional ratio of alumina and silicais 60:40 to 80:20.

It is preferable that a needle-punching treatment be performed withrespect to the mat. When the needle-punching treatment is performed withrespect to the mat, it is difficult for constituent materials such as aninorganic fiber sheet making up the mat to fall to pieces, and thus theconstituent materials have one collected mat shape. In addition, whenthe mat is needle-punched in a lateral direction orthogonal to thelongitudinal direction, it looks like as if the mat is folded at aneedle-punched portion in a lateral direction thereof, and thus when themat is wound around an object, it is easy to wind the mat.

In addition, a product, which is obtained by impregnating an organicbinder such as an acrylic resin into the mat and by subjecting theresultant mat to compression drying to reduce the thickness thereof, maybe used as the heat insulation material 17. After the heat insulationmaterial 17 is wound around the heat absorption body 11, the the heatabsorption body 11 is inserted into the support body 12, and thus theheat absorption body 11 is mounted to the support body 12, when the heatabsorption body 11 is irradiated with reflected light of the solar light18, a temperature of the heat absorption body 11 increases toapproximately 1,000° C. Accordingly, the organic binder is decomposedand eliminated, and thus a compressed state due to the organic binder isopened. As a result, the heat absorption body 11 is reliably held by andfixed to the support body 12. It is preferable that the thickness of theheat insulation material 17 be 3 to 14 mm.

Hereinafter, a method of manufacturing the heat collection receiverrelated to this embodiment will be described.

First, the porous silicon carbide making up the honeycomb unit isproduced.

When producing the porous silicon carbide, as raw materials, siliconcarbide powders having average particle sizes different from each other,an organic binder, a plasticizer, a lubricant, water, and the like aremixed with each other to prepare a wet mixture for molding.

Subsequently, a molding process of putting the wet mixture into anextruder and extrusion-molding the wet mixture is performed to prepare ahoneycomb unit molded body in which a plurality of flow paths are formedin a longitudinal direction and which has a quadrangular prism shape.

Next, a cutting process of cutting both ends of the honeycomb unitmolded body using a cutting device is performed to cut the honeycombunit molded body into a predetermined length, and then the cut honeycombunit molded body is dried using a drying machine.

Next, a degreasing process of heating the organic material contained inthe honeycomb unit molded body in a degreasing furnace is performed, andthe resultant degreased honeycomb unit molded body is conveyed into abaking furnace to perform a baking process to produce a honeycomb unitbaked body (porous silicon carbide). In addition, the honeycomb unitbaked body is simply referred to as a honeycomb unit.

Subsequently, a metal impregnation process of impregnating a metal inthe honeycomb unit baked body is performed. In a case of impregnatingsilicon in the honeycomb unit baked body, for example, it is preferablethat a carbonaceous material be impregnated in the honeycomb unit bakedbody in advance. Examples of the carbonaceous material include variouskinds of organic materials such as a furfural resin, a phenol resin,lignosulfonate, polyvinyl alcohol, corn starch, molasses, coal-tarpitch, and alginate. In addition, pyrolytic carbon such as carbon blackand acetylene black may be similarly used.

The reason why the carbonaceous material is impregnated in the honeycombunit baked body in advance is that a new silicon carbide film is formedon a surface of each open pore of the honeycomb unit baked body, andthus bonding between fused silicon and the honeycomb unit baked bodybecomes strong. In addition, the strength of the honeycomb unit bakedbody increases due to the impregnation of the carbonaceous material.

In addition, as a method of filling open pores of the honeycomb unitbaked body with silicon, for example, a method in which silicon isheated and melted, and then the melted silicon is sucked into the openpores and the pores are filled with the silicon may be exemplified. Inthis case, silicon in a clumped state, a powder shape, or a particleshape is placed on an upper surface or a lower surface (a side surfaceexcluding end surfaces) of the honeycomb unit baked body, the silicon ismelted under a vacuum condition at 1450° C. or higher to fill the openpores of the honeycomb unit baked body with silicon. An impregnationrate of silicon with respect to the honeycomb unit baked body may becontrolled by repeating the above-described process or by changing theweight of silicon that is placed.

In addition, a method, in which pulverized silicon is dispersed in adispersion medium solution, this dispersion medium solution isimpregnated in the honeycomb unit baked body, the resultant honeycombunit baked body is dried, and then the dried honeycomb unit baked bodyis heated to a temperature equal to or higher than a melting temperatureof silicon, may be applicable.

In addition, the metal impregnation process may be performed withrespect to the honeycomb unit molded body (that is, the honeycomb unitbefore the baking process). According to this method, power saving isrealized, and thus manufacturing cost may be suppressed.

According to the above-described method, a silicon-filled honeycomb unitmay be obtained. In regard to the honeycomb unit, one honeycomb unit maybe used as is as the heat absorption body, but a plurality of honeycombunits are bonded with each other using an adhesive and then the bondedhoneycomb units may be used as the heat absorption body. The heatabsorption body in which the plurality of honeycomb units are bonded toeach other through an adhesive layer may be produced by the followingmethod.

That is, when the plurality of honeycomb units are bonded to each otherthrough a silicon layer by using silicon as an adhesive, filling withsilicon with respect to the porous silicon carbide (honeycomb unit bakedbody) and bonding of the plurality of honeycomb units are performedsimultaneously. In this case, for example, the plurality of honeycombunit baked bodies, in which pulverized silicon is impregnated, areassembled to have a shape of the heat absorption body using apredetermined fastening device, and then the resultant assembly isheated. In addition, as another method, it is possible to adopt a methodin which a plurality of honeycomb unit baked bodies into which siliconis not impregnated are assembled, and then silicon is placed on an uppersurface or a lower surface (a side surface excluding end surfaces) ofeach of the honeycomb baked bodies, or the like, and heating isperformed in a vacuum atmosphere. Furthermore, a silicon powder in aslurry state is applied to a side surface of each honeycomb unit bakedbody, and the honeycomb unit baked bodies are heated in a state in whichtwo honeycomb unit baked bodies are brought into contact with each otherthrough an application surface so as to bond the honeycomb unit bakedbodies, and then this processes may be repeated.

According to this method, open pores of each of the honeycomb unit bakedbody (porous silicon carbide) are filled with silicon, and at the sametime, silicon also spreads between side surfaces of the honeycomb bakedbodies to form an adhesive layer, whereby honeycomb unit baked bodiesmay be bonded to each other through silicon.

When forming a porous layer in the honeycomb unit (porous siliconcarbide) that is filled with silicon, it is necessary to remove siliconof a surface region at a predetermined depth from a surface of thehoneycomb unit by etching or the like. Examples of a method for etchingsilicon include wet etching using a liquid, dry etching using a gas, andthe like.

Examples of the wet etching method include a method of etching siliconusing a fluonitric acid obtained by mixing a hydrofluoric acid and anitric acid, potassium hydroxide, tetramethylammonium hydroxide (TMAH),or the like. In addition, examples of the dry etching method include amethod of etching silicon by plasma etching using Freon or the like.

In addition, it is possible to adopt a method in which the honeycombunit filled with silicon is heated under a vacuum atmosphere toevaporate silicon.

Furthermore, the porous layer is formed in the surface region of thehoneycomb unit according to the above-described method, and then theporous silicon carbide in the porous layer may be additionally convertedinto carbon by the above-described method according to necessity.

The support body may be produced by using a method that has been used inthe related art. When producing a support body formed from ceramic, amixture including a ceramic powder, an organic binder, and the like issubjected to compression molding, injection molding, casting molding, orthe like, and then the resultant molded body is subjected to adegreasing process and a baking process, whereby the support body may beproduced.

When assembling the heat collection receiver 10, the heat insulationmaterial 17 is wound around the heat absorption body 11 that is producedby the above-described method, and then the heat absorption body 11around which the heat insulation material 17 is wound is inserted intothe support body 12 and is fixed therein, whereby the heat collectionreceiver 10 may be assembled.

Hereinafter, operation effects of the heat collection receiver of thisembodiment will be described.

(1) In the heat collection receiver of this embodiment, since thehoneycomb unit, which is included in the heat absorption body, includesporous silicon carbide, and silicon that fills pores in the poroussilicon carbide, the honeycomb unit becomes a dense body. Since thehoneycomb unit is a dense body, heat capacity thereof increases, andthus heat accumulation property of the honeycomb unit increases. Inaddition, since the honeycomb unit is a dense body including poroussilicon carbide and silicon, thermal conductivity is high, and it ispossible to smoothly transfer heat that is obtained to a heat mediumsuch as the air.

(2) In the heat collection receiver of this embodiment, since in regardto a surface of the honeycomb unit, which is irradiated with solarlight, a surface region at a predetermined depth from the surface isformed from a porous layer, it is possible to prevent the solar lightfrom being reflected by silicon. In addition, in the heat collectionreceiver of this embodiment, it is easy for solar light to enter theinside of the porous layer of the honeycomb unit, and light reflectedinside the porous layer comes into contact with a separate wall insidethe porous layer of the honeycomb unit. Accordingly, it is difficult forthe reflected light to be emitted to the outside. As a result, theemitted solar light may be effectively converted into heat, and thuspower generation may be effectively performed.

(3) In the heat collection receiver of this embodiment, in a case wherethe porous layer of the surface region of the honeycomb unit is formedfrom a porous carbon layer, a solar light reflectance of the surfacelayer itself decreases, and thus heat absorption efficiency increases.

(4) In the heat collection receiver of this embodiment, flow paths of31.0 to 93.0 per cm² are formed in the honeycomb unit that is includedin the heat absorption body, a thickness of a wall portion between theflow paths in the honeycomb unit is 0.1 to 0.4 mm, a porosity of thehoneycomb unit is 35 to 60%, and an average pore size is 5 to 30 μm.Accordingly, the pores of the honeycomb unit are easily filled withsilicon. In addition, when a heat medium flows through the flow path ofthe honeycomb unit, heat is effectively transferred from the heatabsorption body to the heat medium, and as a result thereof, the powergeneration may be performed with high efficiency.

(5) In the heat collection receiver of this embodiment, a heatinsulation material is interposed between the heat absorption body andthe support body. Accordingly, the heat absorption body is reliably heldby the heat insulation material, and due to this heat insulationmaterial, it is possible to effectively prevent heat from escaping fromthe heat absorption body to the support body.

(6) In the heat collection receiver of this embodiment, the heatabsorption body is configured in such a manner that the plurality ofhoneycomb units are bonded to each other through a silicon layer that isformed on a side surface. Accordingly, the honeycomb units are bonded toeach other in a reliable manner, and thus it is possible to prevent partof the honeycomb units from falling out due to an operation of a forcein a flow direction of the heat medium that flows through the flow pathof the heat absorption body.

EXAMPLES

Hereinafter, examples illustrating a first embodiment of the inventionin more detail are described, but the invention is not limited to thisexample.

Example 1

(Process of Producing Honeycomb Unit Baked Body)

52.8% by weight of silicon carbide coarse powder having an averageparticle size of 22 μm, and 22.6% by weight of silicon carbide finepowder having an average particle size of 0.5μm were mixed with eachother. To the resultant mixture that is obtained, 2.1% by weight ofacrylic resin, 4.6% by weight of organic binder (methyl cellulose), 2.8%by weight of of lubricant (Unilube manufactured by NOF CORPORATION),1.3% by weight of glycerin, and 13.8% by weight of water are added, andthe resultant material was kneaded, whereby a wet mixture was obtained.Next, an extrusion molding process of extrusion-molding the obtained wetmixture was performed, whereby a green honeycomb unit molded body havinga quadrangular prism shape was prepared.

Subsequently, the green honeycomb unit molded body was dried using amicrowave drying machine, whereby a dried body of the honeycomb unitmolded body was obtained.

A degreasing process of degreasing a dried body of the honeycomb unitmolded body at 400° C. was performed, and a baking process was performedunder conditions of a normal pressure argon atmosphere at 2200° C. forthree hours to produce a honeycomb unit baked body formed from siliconcarbide. A porosity of the honeycomb unit baked body was 42%, an averagepore size was 11 μm, a size was 34.3 mm×34.3 mm×45 mm, the number ofcells (cell density) was 50 per cm², and a thickness of a cell wall was0.25 mm (10 mil).

(Silicon Filling Process)

Subsequently, phenol resin (carbonization rate: 30% by weight) wasimpregnated into the obtained honeycomb unit baked body formed fromporous silicon carbide in advance at a normal temperature and a normalpressure, and then the resultant molded body was dried.

Next, particle-shaped silicon was placed on an upper surface and a lowersurface (side surfaces excluding end surfaces) of the honeycomb unitbaked body, and then the honeycomb unit baked body was maintained undera vacuum condition at 1,650° C. for two hours to melt silicon, wherebyopen pores of the honeycomb unit baked body were filled with silicon.

In addition, an impregnation amount of silicon with respect to 100 partsby weight of silicon carbide was set to 40 parts by weight.

Thermal conductivity of the obtained honeycomb unit 13 was 120 W/m·K,and density was 2.80 g/cm³.

Next, silicon that was present in the surface region of the honeycombunit 13 was etched using a fluonitric acid obtained by mixing 49 wt %hydrofluoric acid, 61 wt % nitric acid, and pure water in a volume ratioof 1:1:1. That is, the honeycomb unit 13 was immersed in the fluonitricacid liquid to a depth of 10 mm with a surface irradiated with the solarlight 18 facing a lower side, and was pulled up after one hour. Afterpulling the honeycomb unit 13, the surface region thereof was observed.From the observation, it could be seen that silicon was etched to adepth of 47 μm from the surface, and only the porous layer 13 a of thehoneycomb unit 13 (silicon carbide) remained.

(Binding Process)

Next, heat resistant double-sided tape was adhered to a bonding surfaceof the honeycomb unit 13, and a total of 16 honeycomb units 13 of fourpieces (in a vertical side)×four pieces (in a horizontal side) werebonded to each other through the heat resistant double-sided tape toform the heat absorption body 11.

Example 2

A honeycomb unit 13 in which silicon was etched to a depth of 78 μm fromthe surface of the honeycomb unit 13 and only the porous layer 13 a ofthe honeycomb unit 13 (silicon carbide) remained was obtained in thesame manner as Example 1 except that the honeycomb unit 13 wasimpregnated in the fluonitric acid for two hours. The same bindingprocess as Example 1 was performed using the obtained honeycomb unit 13to produce a heat absorption body.

Example 3

A honeycomb unit 13 was prepared in the same manner as Example 1. Next,the honeycomb unit 13 was immersed in a fluonitric acid having the samecomposition as Example 1 to a depth of 5 mm with a surface irradiatedwith the solar light facing a lower side, and was pulled up after onehour. After pulling the honeycomb unit 13, the surface region thereofwas observed. From the observation, it could be seen that silicon wasetched to a depth of 650 nm (0.65 μm) from the surface of the honeycombunit, and only the porous layer 13 a of the honeycomb unit 13 (siliconcarbide) remained.

Next, a heating treatment was performed with respect to the obtainedhoneycomb unit 13 under a vacuum atmosphere of 0.8 Torr at 1,650° C. for96 hours, and thus silicon was removed from the honeycomb unit 13(porous silicon carbide 16), and silicon carbide was converted intocarbon. The same binding process as Example 1 was performed using thehoneycomb unit that was obtained through the above-described processesto produce a heat absorption body.

Example 4

A honeycomb unit 13 in which silicon was etched to a depth of 78 μm fromthe surface of the honeycomb unit 13 and only the porous layer 13 a ofthe honeycomb unit 13 (silicon carbide) remained was obtained in thesame manner as Example 2. Next, a heating treatment was performed withrespect to the obtained honeycomb unit 13 under a vacuum atmosphere of0.8 Torr at 1,650° C. for 96 hours, and thus silicon was removed fromthe honeycomb unit 13 (porous silicon carbide 16), whereby a honeycombunit of which surface region was converted into carbon was obtained. Thesame binding process as Example 1 was performed using the honeycomb unit13 that was obtained to produce a heat absorption body.

Reference Example 1

A honeycomb unit 13 in which silicon was etched to a depth of 400 nm(0.40 μm) from the surface thereof and only the porous layer 13 a of thehoneycomb unit 13 (silicon carbide) remained was obtained in the samemanner as Example 1 except that the honeycomb unit 13 was impregnated inthe fluonitric acid for one hour. A heat absorption body was produced inthe same manner as the binding process of Example 1 by using theobtained honeycomb unit 13.

Reference Example 2

A honeycomb unit 13 in which silicon was etched to a depth of 400 nm(0.40 μm) from the surface thereof and only the silicon carbide porouslayer 13 a remained was obtained in the same manner as ReferenceExample 1. Next, a heating treatment was performed with respect to theobtained honeycomb unit 13 under a vacuum atmosphere of 0.8 Torr at1,650° C. for approximately 96 hours, and thus the silicon 15 wasremoved from the honeycomb unit 13 (porous silicon carbide 16), wherebya honeycomb unit 13 of which surface region was converted into carbonwas obtained. The same binding process as Example 1 was performed usingthe honeycomb unit 13 that was obtained to produce a heat absorptionbody.

Comparative Example 1

A honeycomb unit 13, in which the porous layer 13 a was not formed andsilicon remained in the surface region of the honeycomb unit 13, wasobtained in the same manner as Example 1 except that the fluonitric acidtreatment was not performed. The same binding process as Example 1 wasperformed using the honeycomb unit 13 that was obtained to produce aheat absorption body.

Comparative Example 2

After a honeycomb unit baked body was produced in the same manner asExample 1, the filling of silicon was not performed. The same bindingprocess as Example 1 was performed using the honeycomb unit baked bodythat was obtained to produce a heat absorption body.

(Evaluation of Sample)

First, as an inorganic fiber mat having a compositional ratio ofAl₂O₃:SiO₂=72:28 (weight ratio), the insulation material 17 in which anaverage fiber length of the inorganic fiber is 5.1 μm, an average fiberlength is 60 mm, a volume density is 0.15 g/cm², and a weight per unitarea is 1,400 g/m² was wound around a side surface of the heatabsorption body that was obtained in each of the examples, referenceexamples, and comparative examples to a thickness of 14 mm. Theresultant objects that were obtained were set as a sample fortemperature measurement (hereinafter, simply referred to as a “sample”).

Next, each sample was irradiated with a film lamp at a distance of 100mm from a sample surface using a spot film lamp RPS-500 WB, 100 V and150 W (manufactured by Panasonic Corporation) for 30 minutes, and atemperature of the sample from initiation of the irradiation to 30minutes after termination of the irradiation) was measured every 10seconds by a thermocouple that was directly attached to the sample.

FIG. 5 shows a graph illustrating evaluation results of Example 1, andComparative Examples 1 and 2. In the graph, the vertical axis representsa temperature (° C.) and the horizontal axis represents an elapsed time(seconds). In addition, evaluation results with respect to all of theexamples, the reference examples, and the comparative examples are shownin Table 1. In Table 1, temperature measurement results (the highesttemperature and temperatures after 30 minutes elapsed from thetermination of the lamp irradiation) of the samples related to therespective examples, comparative examples, and the reference examples.In addition, a silicon impregnation ratio (parts by weight/100 parts byweight of SiC) of the honeycomb unit, thermal conductivity (W/m·K), amaterial of the porous layer, and a thickness of the porous layer wereshown. In addition, measurement of the thermal conductivity wasperformed by a laser flash method.

TABLE 1 Impregnation amount of silicon (parts by weight/100 parts byThermal Material of Thickness The highest Temperature weight ofconductivity porous of porous temperature after 30 SiC) (W/m · K) layerlayer (° C.) minutes (° C.) Example 1 40 120 Silicon   47 μm 74.0 26.8carbide Example 2 40 120 Silicon   78 μm 74.2 26.5 carbide Example 3 40120 Carbon 0.65 μm 75.7 26.5 Example 4 40 120 Carbon   78 μm 75.8 26.7Reference 40 120 Silicon 0.40 μm 71.5 23.9 Example 1 carbide Reference40 120 Carbon 0.40 μm 71.9 23.8 Example 2 Comparative 40 120 Not present  0 μm 71.2 23.7 Example 1 Comparative 0 45 Silicon The 75.6 21.9Example 2 carbide entirety of honeycomb unit

As is clear from results that are shown in FIG. 5 and Table 1, insamples related to Examples 1 to 4, heat from the light is easilyabsorbed and a temperature easily increases compared to samples in whichthe porous layer is not formed on the surface of the honeycomb unit likeComparative Example 1. In addition, in the samples related to Examples 1to 4, heat capacity is large. Therefore, compared to the sample in whichsilicon is not filled like Comparative Example 2, the temperature riseis relatively slower, but a rate of the sample temperature drop is smallafter termination of the lamp irradiation, and a temperature after 30minutes from the termination of the lamp irradiation becomes high in thesample in which silicon is filled.

In addition, as shown in Reference Examples 1 and 2, in a case where thethickness of the porous layer is as thin as 0.40 μm (400 nm), it isconsidered that a solar light absorption rate of the heat absorptionbody decreases a little. The thermal conductivity of Examples 1 to 4 is120 W/m·K, and the thermal conductivity of Comparative Example 2 is 45W/m·K. From these results, it can be seen that the thermal conductivityis improved by impregnating silicon, and thus it is preferable toimpregnate silicon to the honeycomb unit.

Second Embodiment

Hereinafter, a second embodiment that is another embodiment of the heatcollection receiver of the invention will be described. The heatcollection receiver related to this embodiment is configured in the samemanner as the heat collection receiver related to the first embodimentexcept that an adhesive layer is formed by using an adhesive paste asthe adhesive that bonds and binds the plurality of honeycomb units 13.

Therefore, in the following description, a description will be mademainly with respect to the adhesive paste related to this embodiment.

That is, in the first embodiment, in the case of producing the heatabsorption body 11 using the plurality of honeycomb units 13, silicon15, which is the same material as the silicon 15 that fills the insideof the porous silicon carbide 16, is used as the adhesive to bond thehoneycomb units 13 to each other, whereby the heat absorption body 11was produced.

On the other hand, in this embodiment, the honeycomb units 13 are bondedto each other by using an adhesive paste including at least an inorganicparticle and an inorganic binder to produce the heat absorption body 11.The adhesive paste may include an inorganic fiber and/or an organicbinder.

Examples of the inorganic binder contained in the adhesive paste includesilica sol, alumina sol, and the like. These may be used alone, or in acombination of two or more kinds. In regard to the inorganic binder, thesilica sol is preferable. A solid content of this material remains inthe adhesive layer.

In addition, it is preferable that the lower limit of the content of theinorganic binder be 1% by weight by the solid content, and morepreferably 5% by weight. On the other hand, it is preferable that theupper limit of the content of the inorganic binder be 30% by weight bythe solid content, and more preferably 15% by weight. When the contentof the inorganic binder is less than 1% by weight, there is a tendencyfor the bonding strength of the adhesive layer to decrease. On the otherhand, when the content of the inorganic binder exceeds 30% by weight,there is a tendency for the thermal conductivity of the adhesive layerto decrease.

Examples of the organic binder contained in the adhesive paste includepolyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethylcellulose, and the like. These may be used alone, or in a combination oftwo or more kinds. In regard to the organic binder, carboxymethylcellulose is preferable.

It is preferable that the lower limit of the content of the organicbinder be 0.1% by weight by a solid content, and more preferably 0.4% byweight. On the other hand, it is preferable that the upper limit of thecontent of the organic binder be 5.0% by weight by the solid content,and more preferably 1.0% by weight. When the content of the organicbinder is less than 0.1% by weight by the solid content, it is difficultto suppress migration of the adhesive layer. On the other hand, when thecontent of the organic binder exceeds 5.0% by weight by the solidcontent, an amount of organic content, which is decomposed to gases,becomes too much in the adhesive layer, and thus there is a tendency forthe bonding strength of the adhesive layer to decrease.

Examples of the inorganic fiber contained in the adhesive paste includeceramic fibers such as silica-alumina, mullite, alumina, and silica.Theses may be used alone, or in a combination of two or more kinds. Inregard to the inorganic fiber, alumina fiber is preferable.

It is preferable that the lower limit of the content of the inorganicfiber be 10% by weight, and more preferably 20% by weight. On the otherhand, it is preferable that the upper limit of the content of theinorganic fiber be 70% by weight, and more preferably 40% by weight.When the content of the inorganic fiber is less than 10% by weight,there is a tendency for elasticity of the adhesive layer to decrease. Onthe other hand, when the content of the inorganic fiber exceeds 70% byweight, there is a tendency for the thermal conductivity of the adhesivelayer to decrease, and there is a tendency for an effect as an elasticbody to decrease.

Examples of an inorganic particle contained in the adhesive pasteinclude carbide, nitride, and the like. An inorganic powder such assilicon carbide, silicon nitride, boron nitride may be exemplified.These may be used alone, or in a combination of two or more kinds. Inregard to the inorganic particle, silicon carbide that is excellent inthermal conductivity is preferable.

It is preferable that the lower limit of the content of the inorganicparticle be 3% by weight, more preferably 10% by weight, and still morepreferably 20% by weight. On the other hand, it is preferable that theupper limit of the content of the inorganic particle be 80% by weight,and more preferably 40% by weight. When the content of the inorganicparticle is less than 3% by weight, there is a tendency for the thermalconductivity of the adhesive layer to decrease. On the other hand, whenthe content of the inorganic particle exceeds 80% by weight, in a casewhere the adhesive layer is exposed to a high temperature, there is atendency for the bonding strength of the adhesive layer to decrease.

The organic binder contained in the adhesive paste is decomposed andremoved when a temperature of the honeycomb unit rises, but the solidcontent of the other inorganic particle and inorganic binder, and thelike are contained, and thus a sufficient bonding force may bemaintained.

In this embodiment, it is preferable that the adhesive paste contain theinorganic particle, the inorganic fiber, and the inorganic binder, andmore preferably the inorganic particle, the inorganic fiber, the organicbinder, and the inorganic binder.

Next, a method of manufacturing the heat collection receiver related tothis embodiment will be described.

In the method of manufacturing the heat collection receiver related tothis embodiment, the heat collection receiver is also manufactured inthe same manner as the first embodiment except that the adhesive pasteof the above-described configuration is used as the adhesive paste thatbonds the honeycomb units to each other.

That is, when bonding the honeycomb units to each other, the adhesivepaste may be applied to a side surface (a surface in which a flow pathis not formed) to bond the honeycomb units to each other, and then thebonded honeycomb unit may be dried. As a drying condition, for example,120° C. and 3 to 10 hours may be exemplified.

Hereinafter, an operation effect of the heat collection receiver relatedto this embodiment will be described. In this embodiment, in addition tothe operation effects (1) to (5) of the first embodiment, the followingeffect is provided.

(7) In the heat collection receiver of this embodiment, the heatabsorption body is configured in such a manner that the plurality ofhoneycomb units are bonded to each other through the adhesive layer thatis formed on a side surface. Accordingly, the honeycomb units are bondedto each other in a reliable manner, and thus it is possible to reliablyprevent part of the honeycomb units from falling out due to an operationof a force in a flow direction of the heat medium that flows through theflow path of the heat absorption body. In addition, since the adhesivehas heat resistance, the heat collection receiver may be used over along period of time in a stable manner.

Third Embodiment

Hereinafter, a third embodiment that is an embodiment of a solar thermalpower generation device of the invention will be described.

In the solar thermal power generation device related to this embodiment,the heat collection receiver related to the first embodiment is used.

FIG. 3A is a front elevational diagram schematically illustrating areceiver array making up the solar thermal power generation devicerelated to this embodiment of the invention, and FIG. 3B is across-sectional diagram taken along a B-B line of the receiver arrayshown in FIG. 3A.

FIG. 4 an explanatory diagram schematically illustrating a solar thermalpower generation device related to this embodiment of the invention.

In the receiver array 20 shown in FIGS. 3A and 3B, a plurality of heatcollection receivers 10 are disposed in a box-type frame 22 in which asolar light irradiation surface is opened in a state in which a surface,which is irradiated with the solar light 18, of the heat absorption body11 is arranged to face the front side.

That is, a heat medium outlet 12 b of the support body 12 making up theheat collection receiver 10 is coupled to the bottom portion 22 a of theframe 22, and the bottom portion 22 a becomes a closed space 22 cexcluding a portion connected to the tube 22 b. Therefore, the heatmedium 14 such as the air passes through the flow path 13 b formed inthe honeycomb unit 13 and is heated by the heat absorption body 11.Then, the heat medium 14 passes through the heat medium outlet 12 b ofthe support body 12 and is collected at the bottom portion 22 a of theframe 22, and is guided to a steam generator 33, to be described later,through the tube 22 b.

In practice, the tube 22 b, a container that is coupled to the tube 22b, or the like is coupled to a device such as an exhaust pump that sucksthe heat medium 14. Therefore, when the exhaust pump or the like is madeto operate, the heat medium 14 such as the air around the heatcollection receiver 10 passes through the flow path 13 b formed in thehoneycomb unit 13, and the heat accumulated in the heat absorption body11 may be transferred to the heat medium 14 such as the air.

As shown in FIGS. 3A and 3B, the heat medium 14 such as the air aroundthe heat collection receiver 10 is intended to be guided to the flowpath 13 b of the honeycomb unit 13. However, the bottom portion 22 a ofthe frame 22 may be configured as a double structure having twochambers. In this case, the heat medium 14 such as the air does notsuddenly enter the flow path 13 b formed in the honeycomb unit 13,enters one chamber of the two chambers, and enters a space 22 c presentbetween the plurality of heat collection receiver 10. Subsequently, theheat medium 14 is blown out from the gap formed between heat collectionportions 12 a, and immediately enters the flow path 13 b formed in thehoneycomb unit 13 of the heat collection receiver 10.

When being configured as described above, since the heat medium 14 firstperforms heat exchange with the support body of which temperature rises,the heat efficiency further increases.

In the solar thermal power generation device 30 of the embodiment of theinvention, the receiver array 20 is disposed at the highest position ofa central tower 32. A steam generator 33, a heat accumulator 34, a steamturbine 35, and a cooler 36 are sequentially disposed under the receiverarray 20. In addition, a plurality of heliostats 37 are disposed aroundthe central tower 32, but these heliostats 37 are set in such a mannerthat a reflection angle and a rotation direction with a perpendiculardirection made as an axis may be freely controlled. Accordingly, thesolar thermal power generation device 30 is automatically controlled insuch a manner that ever-changing solar light 18 is reflected by theheliostats 37 and is collected by the receiver array 20 of the centraltower 32.

The steam generator 33 is a unit that generates steam to cause the steamturbine 35 to operate. In the steam generator 33, the heat medium 14,which is heated by the heat absorption body 11 of the receiver array 20,passes through the gas tube 22 b and is guided to the pipe of the steamgenerator 33 (boiler). In this pipe, heat exchange between water and theheat medium 14 occurs, and heated water generates water vapor.

The generated water vapor is introduced to the steam turbine 35 andoperates the steam turbine 35 to rotate, and due to this rotation of thesteam turbine 35, a power generator operates and thus electricity isgenerated.

The heat accumulator 34 is a unit that temporarily accumulates the heatthat is obtained by the heat medium 14, and sand is used as a heataccumulation member. In this heat accumulator 34, a heat accumulationpipe (not shown), which is connected to the tube 22 b, is laid in thesand, and the heat medium 14 that is heated by the heat absorption body11 passes through the heat accumulation pipe, whereby heat is suppliedto the sand that is a heat accumulation material. The heat accumulationmaterial has large heat capacity, and thus the heat accumulationmaterial may absorb a large amount of heat and accumulate the absorbedheat. In addition, the heat accumulation material that is accommodatedin the heat accumulator 34 is not limited to the above-described sand,and an inorganic material having large heat capacity other than the sandmay be used, and various kinds of salts or the like may be used.

In the sand of the heat accumulator 34, a steam generation pipe (notshown), that is different from the heat accumulation pipe, is laid inthe sand, and thus during a time such as nighttime at which the solarlight 18 cannot be used, the heat medium 14 that is not heated is madeto flow through the steam generation pipe, and thus the heat medium 14is heated by the sand that is the heat accumulation material of whichthe temperature rises. The heat accumulation pipe may also serve as thesteam generation pipe.

The heat medium 14 that is heated enters the steam generator 33 andgenerates water vapor. Accordingly, as described, the steam turbine 35operates and electricity is generated.

The water vapor that passes through the steam turbine 35 is guided tothe cooler 36, is cooled down by the cooler 36, and becomes water. Aftera predetermined treatment, this water is returned to the steam generator33.

In regard to the cooler 36, it is preferable that the heat medium 14,which is cooled after passing through the steam generator 33, beconfigured to pass through a cooling tube (not shown) of the cooler 36.When passing through the cooling tube, the heat medium 14 is heated, andthus the heat that is absorbed by the heat collection receiver 10 may beeffectively used.

In addition, as described above, in a case where the pipe is configuredin such a manner that the heat medium 14 that collects the heat whichenters the space 22 c that is formed between the plurality of heatcollection receivers 10 of the receiver array 20, the heat of thesupport body 12 of the heat collection receiver 10 may be effectivelyused.

Hereinafter, operation effects of the solar thermal power generationdevice related to the third embodiment will be described.

(1) In the solar thermal power generation device of this embodiment,since the heat collection receiver related to the first embodiment isused, the solar light that is emitted may be effectively converted intoheat, and thus power generation may be effectively performed.

(2) In the solar thermal power generation device of this embodiment,since the receiver array is provided with the plurality of heatcollection receivers, in the solar thermal power generation device, alarge amount of solar heat may be used, and thus a large amount ofelectricity may be generated.

(3) In the solar thermal power generation device of this embodiment,since the heat accumulator is used and the heat that is generated by thesolar light may be stored in the heat accumulator, power generation maybe performed even at nighttime, on a rainy day, or the like at which thesolar light may not be used.

As described above, the solar thermal power generation device of theembodiment of the invention using the heat collection receiver relatedto the first embodiment of the invention was described, but even whenusing the heat collection receiver related to the second embodiment ofthe invention, the same solar thermal power generation device may berealized.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

1. A heat collection receiver comprising: a heat absorption body thatincludes at least one honeycomb unit in which a plurality of flow pathsthrough which a heat medium passes are provided in parallel with eachother, the at least one honeycomb unit including porous silicon carbideand silicon that fills pores in the porous silicon carbide, a surfaceregion of the at least one honeycomb unit including a porous layer whichincludes pores in a predetermined depth from the surface, the surfaceregion being irradiated with solar light, the pores of the porous layerbeing not filled with the silicon; and a support body which accommodatesand supports the heat absorption body and through which the heat mediumflows.
 2. The heat collection receiver according to claim 1, wherein theat least one honeycomb unit further includes porous carbon, and thesurface region of the at least one honeycomb unit includes a porouscarbon layer.
 3. The heat collection receiver according to claim 1wherein the surface region of the at least one honeycomb unit has adepth of 500 nm or more from the surface.
 4. The heat collectionreceiver according to claim 1, wherein the at least one honeycomb unitincludes the flow paths of 31.0 to 93.0 per cm², a thickness of a wallportion between the flow paths in the at least one honeycomb unit is 0.1to 0.5 mm, a porosity of the porous silicon carbide is 35 to 60%, and anaverage pore size is 5 to 30 μm.
 5. The heat collection receiveraccording to claim 1, wherein a heat insulation material is interposedbetween the heat absorption body and the support body.
 6. The heatcollection receiver according to claim 1, wherein the at least onehoneycomb unit includes a plurality of honeycomb units and the heatabsorption body is configured in such a manner that the plurality ofhoneycomb units are bonded to each other through an adhesive layer. 7.The heat collection receiver according to claim 6, wherein the heatabsorption body is configured in such a manner that the plurality ofhoneycomb units are bonded to each other through a silicon layer that isformed on a side surface of the plurality of honeycomb units.
 8. A solarthermal power generation device comprising the heat collection receiveraccording to claim 1.